The invention relates to a method and a system for encasing a pipe conduit, laid in a gallery in an endless manner, with backfill concrete, with a working direction advancing in the axial direction of the gallery.
In particular, the invention relates to the laying of large pipes in galleries, which may be of any desired length. When xe2x80x9cgalleriesxe2x80x9d are referred to below, this is also intended to denote supply tunnels and other channels. In this case, the galleries may be horizontal or also inclined, as used in particular in drinking water supply.
In the present connection, the expression xe2x80x9cbackfill concretexe2x80x9d refers to a product which is pumpable, can be hardened and is suitable for filling in a cavity-free manner by subsequent grouting. Products such as xe2x80x9cFxc3xcllbinderxe2x80x9d from Schwenk Zement and xe2x80x9cDxc3xa4mmerxe2x80x9d from Anneliese are currently on the market. The dry mixture of these products essentially comprises stone dust and cement.
The present invention relates primarily to pipe conduits made of steel; however, it can likewise be used in the case of pipe conduits made of concrete, cast materials or plastic materials.
According to the prior art, for laying pipelines, it is known to move sectional conduits into the galleries and to connect them to one another by means of internal welds. So that the pipelines are firmly embedded in place in the cavities, the pipelines are encased with backfill concrete which should as far as possible completely fill the space between pipe conduit and gallery wall. In addition to the firm embedment of the pipe conduit in the gallery, the backfill concrete, on account of its basic properties, additionally assumes the function of the anti-corrosion protection of the otherwise unprotected steel lines.
In detail, the procedure is as follows: the pipes are introduced in sectional conduits into the cavity and are connected to one another there up to a maximum length of 100 m and are attached to the already encased pipe conduit. There are often considerable technical difficulties when bringing the new sectional conduit together with the fixed pipe end, since the freedom of movement of the sectional conduit is very restricted as a result of the move-in construction and the uplift safety features. After the advance of a pipeline of a maximum length of one hundred meters, the annular space at the open line end is partitioned for the filling.
The partition is provided with complicated rubber seals in order to produce the pressure-tight closure between pipe outer wall and cavity inner wall. In addition, the partition worked fair on one side must be solidly supported at the free inside of the cavity on 20 account of the filling pressure to be expected, as a result of which the accessibility to the partition is considerably restricted.
The annular space is filled with backfill concrete in a single operation via the delivery lines directed through the partition. Uplift safety features along the pipeline absorb the full uplift on the pipeline in the roof region. Uplift movements of the pipeline produce deformations in the region of the partitioning and lead to leakages during the filling operation. Due to sudden superimposition of liquid pressure and filling pressure toward the end of the filling, there is the risk of the partition being pressed to an excessive degree and of the backfill concrete pouring into the working space.
The still full delivery lines are to be emptied through a return line and are to be cleaned; the filling material is to be disposed of. After the backfill concrete starts to harden (about 3 days), the settling space at the roof can be grouted. This residual-space grouting is effected over the entire section length (100 m) from the partition region. Due to the fact that the operation for cleaning the delivery lines is complicated, the mixing of the dry material is effected upstream of the partition. The material required for this and the machines are to be introduced separately and removed again. The partition cannot be removed until after the consolidation of the backfill concrete at the roof.
No pipe construction can take place during the filling of the annular space up to the time when the partition is removed. During the period of the subsequent pipe construction, no filling work can be carried out. Since this involves underground working, the normal working day is 24 hours. Pipe-laying work and filling work are carried out by different professional groups in shift work. Since the laying work and the filling work cannot be carried out in parallel and there are in addition long periods of unavoidable interruptions of work on account of the setting process, this work cannot be carried out efficiently.
The settling volume of the backfill concrete is 3%. A large settling volume is produced by filling the annular space in one operation. By subsequent grouting of this settling space in a separate operation, a relatively large settling volume is again produced, which may be the cause of undesirable conductivities (water course and gas accumulation) at the cavity roof. Filling at the roof in a cavity-free manner is not ensured. In the long term, soil settlement due to a cavity which is not grouted is to be expected.
The object of the present invention is essentially to specify a method and a corresponding system in which the production costs in particular can be reduced by virtue of the fact that the laying of the pipe conduit on the one hand and the encasing of the pipe conduit with backfill concrete on the other hand can be carried out in parallel.
With regard to the method, this object is achieved according to the invention essentially by the following method steps:
a) dividing the gallery including the pipe conduit into sections of preferably equal length,
b) producing an opening at the pipe apex in each section,
c) introducing the backfill concrete layer by layer through the pipe conduit and through the opening of each section, at least the introduction of the respectively last layer preferably being effected in sections following one another in the working direction, and
d) closing the openings of the filled sections.
The essence of the invention therefore lies in the fact that the introduction of the backfill concrete into the cavity surrounding the pipe conduit is effected solely from the interior of the pipe conduit, so that the pipe conduit can be laid without hindrance. The separation of pipe laying and pipe encasing into work cycles independent of one another guarantees an undisturbed continuous working method with execution quality and economical production costs. Therefore, while the backfill concrete is introduced, if need be in a loose sequence, section by section the opening produced beforehand is closed again, the pipe-laying work can be carried out in an undisturbed manner at the front as viewed in the working direction.
In an especially preferred further development of the method according to the invention, the following further steps are provided:
e) fastening of subsequent-grouting lines in each section, these subsequent-grouting lines running at the roof of the gallery in the axial direction and ending above the opening, to be precise before the method step c), and
f) after method step c), subsequent grouting by introducing backfill concrete into the subsequent-grouting lines through the pipe conduit and through the respective opening.
Once the backfill concrete has settled to a certain extent during its hardening, a cavity occurs at the roof of the gallery, and this cavity can be filled reliably and completely via the firmly installed subsequent-grouting lines. In this way, encasing of the pipe conduit in a virtually cavity-free manner is possible.
Furthermore, in a preferred development of the invention, provision is made for flow barriers to be fitted at the respective section boundaries before method step c), which flow barriers may in particular be produced from like-grained concrete. The placement of such flow barriers below the pipe bottom, which is preferably effected in the course of the continuous pipe laying, limits the respective section of the cavity filling in the critical uplift region. The uplift force of the backfill concrete must not exceed the weight of the pipeline. The flow barriers of like-grained concrete are placed during the continuous pipe laying preferably at least up to the level of the equilibrium limit between pipe weight and uplift force.
In an advantageous development of the invention, the introduction of the backfill concrete layer by layer is effected in the following steps:
c1) introduction of at least one filling layer until the pipe-conduit section of a section has not quite started to float on the filling layer,
c2) introduction of a second filling layer of specifically lighter backfill concrete after the settling and consolidation of the first filling layer, and
c3) introduction of further filling layers after at least partial consolidation of the preceding layer.
The introduction of the second filling layer of specifically lighter backfill concrete serves to close the settling gap produced at the pipe and to ensure the adhesion forces between pipe and backfill concrete.
With regard to the system, the object mentioned further above is essentially achieved in that the following is provided in each section:
a reclosable opening at the pipe apex,
a filling connection which is fastened in the region of the opening to the pipe conduit and is oriented perpendicularly upward,
a pressure line, which runs in the interior of the pipe conduit and can be releasably connected to the filling connection, for backfill concrete,
at least one firmly installed subsequent-grouting pipeline arrangement which is arranged at the roof of the gallery and ends in the region of the filling connection, and
at least one subsequent-grouting line which runs in the interior of the pipe conduit and can be releasably connected to the filling connection instead of the pressure line and can be connected to the at least one firmly installed subsequent-grouting pipeline arrangement.
To fill the cavity, first of all the pressure line is attached to the respective pipe connection and the sections in question are filled completely layer by layer. After the backfill concrete has settled, the subsequent-grouting line is connected through the filling connection to the firmly installed subsequent-grouting pipeline arrangement and subsequent grouting is effected. After the opening is closed again, the firmly installed subsequent-grouting pipeline arrangement remains in the gallery.
Since the opening of each section is arranged between the two ends of the section, two firmly installed subsequent-grouting pipeline arrangements are preferably provided, and these subsequent-grouting pipeline arrangements extend from the opening or from the filling connection essentially in opposite directions in order to cover essentially the entire section.
In a preferred development of the invention, each subsequent-grouting pipeline arrangement has a pipe section with a number of radial through-holes which are distributed over the pipe section and are closed to begin with, in particular by means of adhesive tape, so that they do not become clogged during the filling with backfill concrete. It is not until the subsequent-grouting device is activated that these through-holes open on account of the high pressure, and backfill concrete can escape outward through the through-holes and fill the remaining cavity.
According to a further advantageous feature of the invention, a line for supplying flushing water is also provided, which line runs in the interior of the pipe conduit and can be releasably connected to the filling connection instead of the pressure line for backfill concrete. This water flushing is activated before the introduction of the last layer or after the introduction of the last layer in the respectively preceding section in order to ensure the conductivity for the subsequent filling.